Ventricular assist device for intraventricular placement

ABSTRACT

The present invention, in one embodiment, is a blood pump for intraventricular placement inside a heart of a mammalian subject including a rigid elongate member having a length between proximal and distal ends and a bore extending along the length, an anchor element connected towards the proximal end of the rigid elongate member and mounted to the subject&#39;s heart, a pump having an inlet and an outlet, a rotor and at least one electric drive coil for magnetically driving the rotor, the pump connected at or adjacent to the distal end of the rigid elongate member remote from the anchor element and wiring extending through the bore to the pump, wherein the proximal end of the rigid elongate member extends past the anchor element to a position outside of the subject&#39;s heart. Additional embodiments of a blood pump, and various methods of intraventricular placement inside a heart of a mammalian subject are also considered.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/471,783, filed on Aug. 28, 2014, which is a divisional ofU.S. patent application Ser. No. 12/322,746, filed Feb. 6, 2009, whichclaims the benefit of the filing date of U.S. Provisional PatentApplication No. 61/065,140, filed Feb. 8, 2008, the disclosures of whichare hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to intraventricular placement of aventricular assist device, to components useful in such devices, and tomethods of using the same.

In certain disease states, the heart lacks sufficient pumping capacityto meet the needs of the body. This inadequacy can be alleviated byproviding a mechanical pumping device referred to as a ventricularassist device (“VAD”)to supplement the pumping action of the heart.Considerable effort has been devoted to providing a VAD which can beimplanted and which can remain in operation for months or years to keepthe patient alive while the heart heals, or which can remain inoperation permanently or until a suitable donor heart becomes availableif the heart does not heal.

The VAD is typically connected to the heart, most commonly to the leftventricle. For example, a VAD may include a pump which is installed inthe body outside of the heart. The VAD may have an inlet cannulaconnected to the interior of the left ventricle and connected to theintake of the pump. The VAD may also include an outlet tube connectedbetween the outlet of the pump and the aorta. Once connected, the VADand the heart both pump blood from the left ventricle to the aorta.

As described, for example, in the U.S. Pat. Nos. 5,376,114 and 6,217,541certain VADs having pumps are arranged so that at least a portion of thepump is disposed within the heart when the VAD is implanted within thepatent. These VADs incorporate pumps which are connected to separateelectric motors by enlongated driveshafts. Such shaft-driven pumpssuffer from significant drawbacks. Commonly assigned, copending U.S.patent application Ser. No. 12/072,471, the disclosure of which ishereby incorporated by reference herein, discloses the VAD having aunitary pump and motor adapted for positioning within the arterialsystem as, for example, within the aorta.

Despite the considerable effort devoted to improvements in VADs, stillfurther improvement would be desirable.

SUMMARY OF THE INVENTION

The words “proximal” and “distal” are used herein to denote directionsand ends of the device and components. As used herein, when referringthe ventricular assist device or components, the term “proximal” refersto the direction toward the surgeon or other operating room personnelduring installation of the device and the term “distal” has the oppositemeaning.

One aspect of the present invention provides a ventricular assist devicefor intraventricular placement inside a heart of a mammalian subject.The device preferably includes an anchor element such as a ringconfigured to be mounted adjacent an apex of the subject's heart, andalso desirably includes an elongate member having proximal and distalends. The device according to this aspect of the invention desirablyalso includes a pump having a housing, an inlet and an outlet a rotorwithin the housing and electric drive coils carried on the housing formagnetically driving the rotor. Preferably, when the device is implantedin the heart, the anchor element and the pump are fixed to the rigidelongate member remote from one another so that the rigid elongatemember maintains the pump in position relative to the anchor element andhence with respect to the heart.

In certain embodiments of the device according to this aspect of theinvention, the pump may have an axis extending between the inlet andoutlet and the rigid elongate member may have an axis offset from anaxis of the pump housing. Preferably, the elongate member extendssubstantially parallel to the axis of the pump.

The elongate member may include a bore extending in the proximal anddistal directions thereof, the device further comprising wiringextending through the bore to the pump. The device may further include atubular outflow cannula defining a bore, the bore having an inlet at aproximal end thereof connected to the outlet of the pump. The outflowcannula preferably includes a tip at the distal end thereof, the tiphaving at least one opening and desirably having a plurality ofopenings. Preferably, the tip of the outflow cannula projects through anaortic valve but terminates short of the arch of the aorta.

Another aspect of the present invention provides a ventricular assistdevice for intraventricular placement inside a heart of a mammaliansubject. The device preferably includes an anchor element such as a ringconfigured to be mounted adjacent an apex of the subject's heart, andalso desirably includes an elongate member having proximal and distalends. The device according to this aspect of the invention desirablyalso includes a pump having a housing, an outflow cannula preferablyhaving a tip at the distal end thereof. Preferably, the tip of theoutflow cannula projects through an aortic valve but terminates short ofthe arch of the aorta. The ring and the pump are connected to the rigidelongate member remote from another so that the rigid elongate membermaintains the pump in position relative to the anchor element.

A further aspect of the present invention provides a method ofinstalling a ventricular assist device in a mammalian subject. Themethod according to this aspect of the invention desirably comprisesmounting a pump to the subject so that an inlet of the pump communicateswith the left ventricle of the heart, and positioning an outflow cannulaof the pump so that the outflow cannula extends from within the leftventricle through the aortic valve but terminates short of the arch ofthe aorta.

Yet another aspect of the present invention provides additional methodsof placing a ventricular assist device at a location inside a heart of amammalian subject. The method according to this aspect of the inventiondesirably comprises providing an anchor element such as a ring and apump to an elongate member remote from one another so that the elongatemember maintains the pump in position relative to the anchor element,advancing the pump through an opening in an apex of the subject's heartand into an intraventricular region of the subject's heart, and mountingthe anchor element to an apex of the subject's heart. Preferably, thepump further comprises a tubular outflow cannula, and the pump andcannula are positioned by the anchor element and elongate member so thatthe tip of the outflow cannula projects through the aortic valve butterminates short of an arch of the aorta.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic ventricular assist device according the presentinvention.perspective view of a to one embodiment of the presentinvention.

FIG. 2 is diagrammatic perspective view of the device of FIG. 1 from adifferent perspective.

FIGS. 3 and 4 are perspective views of certain components used in thedevice of FIG. 1.

FIGS. 5 and 6 are perspective interior views depicting certain portionsof the device shown in FIG. 1.

FIGS. 7 a, 7 b and 7 c are fragmentary views depicting a portion of acomponent used in the device of FIG. 1.

FIGS. 8 a and 8 b are diagrammatic perspective views depicting portionsof devices according to further embodiments of the invention.

FIGS. 9 and 10 are diagrammatic views of the ventricular assist deviceof FIG. 1 in an installed condition, in conjunction with the certainstructures of the heart.

FIG. 11 is a diagrammatic perspective view depicting portions of adevice according to a further embodiment.

FIG. 12 is a diagrammatic perspective view along line A-A in FIG. 1.

FIGS. 13-19 are diagrammatic perspective views depicting portions ofdevice according to still further embodiments.

DETAILED DESCRIPTION

Referring to the drawings, wherein like reference numerals refer to likeelements, there is shown in FIGS. 1-2, an embodiment of the ventricularassist device of the present invention designated generally by referencenumeral 10. As shown in those figures, device 10 has four distinctsections including a pump 20, an outflow cannula 40, a rigid elongatemember 60, and a ring 80.

Pump 20 is shown in FIGS. 2-5. Pump 20 is an axial flow pump having aninlet 21 and an outlet 23 arranged on an axis 19 referred to herein asthe pump axis. The pump has an axial bore defined by a tubular housing22 which extends between the inlet and the outlet. Housing 22 is formedfrom biocompatible materials such as ceramics and metals such astitanium. The materials used for those portions of the housing disposedinside the motor stator discussed below desirably are non-magneticdielectric materials such as ceramics.

A motor stator 24 is disposed around the outside of tubular housing 22.The motor stator is arranged to provide a rotating magnetic field.Preferably, stator 24 contains both magnetic laminations and wire coils(not shown). Sequencing the electrical current through the wire coilsproduces the rotating electromagnetic field necessary. Stator 24 can bea conventional slotted or slotless design or may utilize a toroidaldesign.

A rotor 26 is disposed within bore 29 shown in FIG. 6, in alignment withstator 24. Rotor 26 may be formed from a unitary piece of amagnetizable, biocompatible platinum-cobalt or platinum-cobalt-boronalloy. The rotor has a central axis coincident with pump axis 19, andincludes a plurality of blades 34 projecting outwardly from such axisand curving around the axis in a generally helical pattern having apitch angle which varies along the axial length of the rotor. The bladesdefine flow channels 36 between them. Blades 34 may be configured sothat their circumferential surfaces act as hydrodynamic bearings.Multiple hydrodynamic bearing surfaces may be provided on each blade,spaced along the axial length of the rotor, for greater hydrodynamicstability during operation. These rotor blades 34 may be magnetized formagnetic coupling to motor stator 24. The number of rotor blades 34 ispreferably either two or four for symmetry of magnetic poles. Duringoperation, the rotor is driven in rotation at a high rotational speed,typically about 8000 to about 40,000 rpm, and preferably between about15,000 to about 25,000 rpm. The rotor blades impel blood within thehousing axially, toward the outlet 23.

The features of the rotor and stator may be generally as shown in theaforementioned copending, commonly assigned U.S. patent application Ser.No. 12/072,471. However, the pump of this embodiment typically is largerthan a pump intended for positioning within an artery. For example, thepump used in this embodiment may be about 21 mm outside diameter andabout mm long, and may have a rotor about 10 mm in outside diameter,.The pump desirably is arranged to deliver about 4 to 6 L/min flow rateagainst a pressure head of about 100 mm Hg. As an alternative to theunitary magnetic rotor discussed above, a conventional rotor designinvolving placement of magnets sealed within a rotor formed fromnon-magnetic material may be used.

The pump also includes diffuser blades 28 are mounted within housing 22downstream from rotor 26, between the rotor and the outlet 23. As bestseen in FIGS. 3, 5, and 6, each diffuser blade is generally in the formof a plate-like vane secured to the housing and projecting radially intothe bore from the wall of the housing. As best seen in FIG. 3, theupstream ends of the diffuser blades 28, closest to rotor 26, curve in acircumferential direction around the axis 19. The direction of curvatureof the diffuser blades is opposite to the direction of curvature of therotor blades. Preferably, the number of diffuser blades is unequal tothe number of rotor blades, and the number of diffuser blades is not anintegral multiple or divisor of the number of pump blades. Thus, wherethe rotor has an even number of blades, the pump desirably has an oddnumber of diffuser blades, such as three or five diffuser blades 28.This arrangement helps to maximize the stability of the rotor andminimize vibration in operation of the pump. However, it should beunderstood that two, four, or more than five diffuser blades 28 may beutilized. During operation, the blood passing downstream from the rotorhas rotational momentum imparted by the rotor. As the blood encountersthe diffuser blades, this rotational momentum is converted to axialmomentum and pressure head. Thus, the diffuser blades serve to reclaimthe energy used to create the rotational motion and convert that energyto useful pumping work. In this embodiment, the diffuser blades are notattached to one another at the axis. This arrangement conserves spacewithin the bore, and thus maximizes axial flow.

Pump 20 has an exterior shroud surrounding the housing 22 and motorstator 24. The shroud may be formed from a biocompatible metal such astitanium, a ceramic, or a biocompatible polymer. Exteriorthromboresistant coatings may also be utilized to improvehemocompatibility. The shroud defines a first attachment portion 30 atthe proximal end of the housing, near inlet 21. The first attachmentportion 30 (FIG. 2) has a recessed cavity 38 which extends into theshroud in a direction parallel to pump axis 19 but offset from the pumpaxis.

The apparatus also includes an elongate member 60 which has a proximalend 61, a distal end 63 and a bore 62 therethrough. Preferably, elongatemember 60 has an axis along its direction of elongation which axis isparallel to the axis 19 of the pump body but offset from axis 19 in adirection transverse to both axes. Merely by way of example, elongatemember 60 may be a tube formed from titanium or other biocompatiblemetal. Member 60 desirably is substantially rigid. That is, the memberdesirably is rigid enough to maintain the pump 20 in position, with nosubstantial movement relative to the ring 80 under the loads normallyapplied to the system while the system is in place within the heart.Elongate member 60 preferably has a spherical ball 90 mounted along thelength thereof, remote from the distal end 63. Ball 90 desirably isfixedly attached to member 60 as, for example, by welding.

The distal end 63 of member 60 is received in recess 38 of firstattachment portion 30 of the pump 20. Preferably, the distal end ofmember 60 is joined to the attachment portion of the pump by apermanent, fluid-tight connection as, for example, by welding member 60to the pump shroud. Electrical power wiring 67 extends from the stator24 of the motor through bore 62 of member 60 and out of the memberthrough a fitting 100 at the proximal end of the member. Preferably,there is a fluid-tight feedthrough (not shown) at fitting 100, at theconnection between the distal end 63 and the attachment portion of thepump, or both. The electrical wiring extends out of the fitting 100 to asource of electrical power (not shown) external to the body of thepatient or implanted within the body of the patient. Preferably, thepower source is a transcutaneous energy transfer or “TET” device. Such adevice includes an implantable unit which has a battery and an inductioncoil. The implantable unit typically is mounted remote from the heart,near the patient's skin. Energy is supplied to the induction coil of theimplantable unit by an induction coil incorporated in an external unitworn by the patient. The internal battery provides continued operationduring intervals when the patient is not wearing the external unit.

An outflow cannula 40 of extends distally from distal end 27 of pump 20.Outflow cannula 40 is generally in the form of a hollow tube having aproximal end attached to pump 20 and communicating with the outlet 23(FIG. 3) of the pump. The outflow cannula has a tip 70 at its distal 20end.

Preferably, outflow cannula 40 is a single molded polymer piece made ofthermoplastic polyurethan(segmented and/or of thermoplasticcopolymerized with silicone, polycarbonate-urethanes,polyether-urethanes, aliphatic polycarbonate, or other additives),silicone, polycarbonate-urethanes, polycarbonate, silicone metals andpossibly polyether-urethanes, material with or without sulfonatedstyrenic aliphatic catalyst polymers. Preferably, outflow cannula 40 maybe cast with or without titanium wire structures for bend enhancementproperties and non-invasive visualization of a catheter typically underx-ray or fluoroscopy. The outflow cannula 40 may contain barium sulfateor other minerals, or metallic marker bands to provide landmark locationvisualization by fluoroscopic, CAT or other radiological techniquesduring or after implantation in the patient.

Outflow cannula 40 may be straight or bent and desirably has anappropriate stiffness and hardness to accommodate the native heart andaortic root geometry and also to have non-traumatic contact withtissues. The diameter of the cannula can be tapered from pump body 20 toa smaller diameter near the distal end of the cannula. As furtherdescribed below, the distal end of the cannula will project through theaortic valve when the apparatus is implanted in a patient. A cannulawhich tapers in diameter towards its distal end provides relatively lowflow resistance due to its large diameter at the proximal end, but alsoprovides a desirable small diameter portion at the aortic valve. Thesmall-diameter portion at the aortic valve helps to minimize aorticvalve insufficiency, i.e. retrograde flow through the valve due to poorsealing of the tri-leaflets around the cannula. Desirably, the cannulais round in cross-section, at least in the region near tip 70 which willextend through the aortic valve when implanted. A round cross-sectionalshape also minimizes aortic valve insufficiency. Merely by way ofexample, a cannula for carrying about 5 l/min of blood may have a meaninterior diameter of about 6 mm.

As best seen in FIGS. 7A-7C, tip 70 has a circumferential surface whichtapers inwardly toward the axis of the cannula in the distal direction,and thus converges toward the distal extremity 74 of the cannula. In theembodiment illustrated, the distal surface of the tip defines a smooth,dome-like shape at the distal extremity of the tip. A plurality ofopenings 72 extend through the circumferential surface of the tip.Openings 72 communicate with the interior bore of the cannula. Whenblood is discharged through openings 72, the flow has a radialcomponent, and will provide a hydrodynamic self centering force forcannula 40. The centering action is believed to further minimize aorticvalve insufficiency. Moreover, even if the cannula tip is restingagainst an arterial wall, the plural openings spaced around thecircumference of the tip will still provide good blood flow. The tip 70geometry is described in more detail in U.S. Provisional PatentApplication No. 61/135,004, filed Jul. 16, 2008, and entitled “CANNULATIP FOR USE WITH A VAD,” which application is hereby incorporated byreference in its entirety in the present application.

A family of outflow cannula 40 sizes developed to better accommodate thevariety of native heart sizes. It is preferred that he may be patentoutflow cannula is preattached to pump 20; however, various cannulasizes may be supplied with the device for attachment in the operatingroom prior to implantation. The attachment between the outflow cannulaand the pump may be of any configuration suitable for maintaining theproximal end in place. The proximal end of the cannula may extend overthe distal end of pump housing 22, and may be secured in place by anadhesive bond. Alternatively, a crimp ring may surround the proximal endof the cannula, so that the wall of the cannula is held between thecrimp ring and the pump housing.

In this embodiment, the device 10 also includes an anchoring element inthe form of a ring 80. Preferably, ring 80 is adapted for mountingadjacent the apex of the patient's heart by sewing around a perimeter ofring 80 to tissue along a wall of the patient's heart. For example, ring80 may be a metallic structure having a peripheral flange with numerousholes for sewing or stapling the ring to the heart wall. The peripheryof ring 80 may be covered with a fabric material such as for examplepolyester material, expanded polytetrafluoroethylene, felt or the likefor promoting tissue growth over the ring to further secure the ring inplace. U.S. patent application Ser. No. 11/289,410, entitled “IMPLANTCONNECTOR,” teaches such a ring component and is herein incorporated byreference in its entirety in the present application.

Ring 80 preferably includes a spherical socket 84 adapted to engage thespherical ball 90 of elongate member 60 such that ring 80 is pivotallymounted to elongate member 60 remote from pump 20. In the embodimentdepicted, the pivotable connection between the ring and the ball may bea permanent connection formed during manufacture. For example, ball 90may be entrapped between elements of the ring which are permanentlyconnected to one another during manufacture. Ring 80 is configured toalign to the heart wall but can also allow for rotational movement toaccommodate the native heart movement.

In a method of implantation according to one embodiment of theinvention, the apparatus discussed above, including the ring 80, member60, pump 20 and outflow cannula 40 is provided as a pre-assembled unit.The surgeon gains access to the heart, preferably using a left subcostalor left thoracotomy incision exposing the left ventricular apex. Apledgeted purse string suture is then applied to the epicardiumcircumferentially over the pump insertion site. A slit incision or anincision in the form of a cross or X, commonly referred to as a “crux”incision, is made through the apex of the heart into the interior of theleft ventricle using a cutting instrument such as a scalpel. Pump 20,member 60 and outflow cannula 40 are then inserted through the cruxincision or slit incision and positioned within the left ventricle sothat cannula 40 extend through the aortic valve into the aorta. Ring 80is positioned on the outside of the heart as depicted in FIGS. 9 and 10.Proper placement of the components can be verified by fluoroscope orother imaging technique. After placement, the pump can be started byapplying electrical power from the external or implantable power source,and proper outflow may be verified using echocardiography. After outflowis verified, crux incision is closed around member 60, as by suturing,and ring 80 is secured to the exterior of the cardiac wall.

As shown in FIGS. 9 and 10, in the implanted condition, ring 80 ismounted adjacent the apex of the subject's heart. Ring 80 and pump body20 are connected to elongate member 60 remote from one another so thatrigid elongate member 60 maintains pump 20 in position relative to ring80. This maintains the pump and outflow cannula 40 in position relativeto the heart.

The aortic valve is one of the valves of the heart. It lies between theleft ventricle and the aorta. The ascending aorta 108 (FIG. 10) is aportion of the aorta commencing at the upper part of the base of theleft ventricle. The arch of the aorta 110 also known as the transverseaorta begins at the level of the upper border of the second sternocostalarticulation of the right side, and runs at first upward, backward, andto the left in front of the trachea. It is then directed backward on theleft side of the trachea and finally passes downward on the left side ofthe body of the fourth thoracic vertebra, at the lower border of whichit becomes continuous with the descending aorta 112.

When the device is in the implanted condition shown in FIG. 9, theoutflow cannula 40 projects through the aortic valve into the ascendingaorta, but most preferably terminates proximal to the arch 110 of theaorta. Thus, tip 70 of cannula 40 is disposed distal to the aortic valveof the subject's heart, but the distal extremity 74 of the tip isproximal to the aortic arch. This position of the outflow cannula 40 isadvantageous in that it minimizes contact between the outflow cannulaand the walls of the aorta, and thus minimizes trauma andthrombogenesis. The secure positioning of the pump 20 and outflowcannula 40 relative to the heart, provided by ring 80 and member 60,help to allow positioning of the cannula tip just distal to the aorticvalve. Because the device is securely held in place within the heart,there is no possibility that movement of the cannula relative to theheart will allow the tip to move proximally, into the ventricle.

In the implanted condition, the axis 19 of the pump extends near theapex of the heart, and the inlet 21 of the pump is aimed generally inthe direction toward the apex of the heart. The length of elongatemember 60 is such that the inlet 21 of pump 20 is remote from the aorticvalve. This position and orientation provide certain advantages. Fibrousstructures of the aortic valve, just 30 proximal to the opening of thevalve, do not get sucked into the inlet of pump 20. Moreover, the inletof the pump will not be occluded by the ventricular wall or theinterventricular septum of the heart.

The ventricular assist device according to the embodiment discussedabove thus provides an intra-ventricular, full output, wearless bloodpump that is sized for thoracotomy, sub-costal or other implantationmethod not requiring a sternotomy. The majority of the device sitswithin the left ventricle and pumps blood distal to the aortic valve toprovide cardiac assistance. The patient population which is typicallysuited for implantation of this device is similar to the biventricularpacing population; congestive heart failure patients who are failingmedical therapy and are willing to undergo a 4 to 6 hour procedurerequiring a maximum hospital stay of approximately five days. Thesepatients are very sick and will need 4 to 6 L/min of support initiallyand may only need 2 to 3 L/min for long term.

Numerous variations and combinations of the features discussed above canbe used. For example, device 10 may include dip molded coating of a thinsilicone or other polymer around of the exterior of the pump 20, rigidelongate member 60 and ring 80. A dip molded polymer may also bemodified by heparin, antithrombotic agents, endothelial tissue growthfactors, antibiotics or hydrophilic gels. By extension of the dipmolding process as described above the outflow cannula may be formed bythe same dip molding process, using a disposable inner core which isremoved from the dip-molded cannula before the apparatus is used. Such aprocess can form the cannula without seams or attachment apparatus as anintegral part of the pump housing, and continuous with aforementioneddip coated elements. The anchoring element may be formed or sheathed bydip molded polymer.

In a further variant, the spherical ball 90 used in the arrangement ofFIG. 1 is fixed within the spherical socket of the ring or otheranchoring element. In yet another variant, the spherical ball and socketmay be replaced by a pivotable joint which allows pivoting movement ofthe anchoring element about just one axis of rotation. In furtherembodiments, the position of the anchoring element may be adjustablealong the length of the elongated element. For example, the anchoringelement or ring may include a gripper arranged so that the gripper maybe tightened around the elongated member by rotating or otherwise movingone portion of the anchoring element relative to another portion, and sothat the gripper may be locked in a tightened condition. For example,the anchor element may incorporate a collet and collet chuck similar tothose used to hold machinist's tools. In yet another variant, theelongated member may be threadedly engaged with the anchoring element sothat the position of the anchoring element may be adjusted towards andaway from the pump by rotating the anchoring element, and then locked inposition using a lock nut or other device to prevent further rotation.In still further variants, the elongated member may have appreciableflexibility while still having enough rigidity to maintain the pump andoutflow cannula in position. For example, the elongated member 60 may beformed as an elongated coil spring of relatively stiff wire. Theelectrical wiring extending within the elongated member may be coiled orotherwise convoluted to provide increase resistance to fatigue inflexing.

FIGS. 8 a and 8 b show two alternative configurations of the elongatemember and anchoring element. As seen in FIG. 8 a, the elongate member160 has a ring or anchoring element 102 disposed near the proximal endthereof. Anchoring element 102 has a tapered distal surface 103 andproximal surface 105 which extends substantially perpendicular to theaxis of elongation of member 160. In the implantation procedure,anchoring element 102 is advanced into the interior of the ventriclethrough the crux incision. The incision is closed around the portion ofmember 160 lying proximal to surface 105, leaving surface 105 of theanchoring element engaged with the interior surface of the myocardium.Purse string sutures may be used on the external myocardium surfaceAnchoring element 102 acts in a similar manner to the anchoring elementor ring 80 discussed above, to prevent axial translation of theelongated member, pump and outflow cannula relative to the heart. Whenimplanted in this manner, the myocardium is closed around that portionof elongate member 160 proximal to anchoring element 102. At thisregion, rigid member 60 optionally may be provided with a roughenedsurface, as by sintering, to promote tissue ingrowth for hemostasis.Alternatively, this portion of the elongated member may be left smooth.An interior anchoring element such as member 102 may be used in lieu of,or in addition to, an exterior securement member such as the ring 80discussed above.

The apparatus shown in FIG. 8 b is similar to the apparatus of FIG. 8 a,except that the elongated member includes a larger diameter stem section104 extending proximally from the anchoring element. The enlargedsection 104 provides greater surface area for tissue ingrowth. Thesurface of section 104 may be treated to enhance tissue ingrowth as, forexample, by sintering.

In still other configurations, the anchor element may not be a roundring but instead may include one or more feet projecting laterally fromthe elongated member near the proximal end thereof, the feet beingarranged to engage the inside, outside or both of the heart walladjacent the apex of the heart. Alternatively, the anchor element may benon-circular in cross-section. For example, the anchor element may haveother geometric configurations such as triangular, oval, elliptical, orthe like.

The elongate member may have various configurations. It should beunderstood that these alternative configurations are merely exemplaryand different configurations may be used without departing from thescope of the present invention. As shown in FIGS. 11-12, an elongatemember 160 has a proximal end 161, a distal end 163 and a bore 162therethrough. In this embodiment, elongate member 160 has an axis alongits direction of elongation which axis is parallel to the axis 119 ofthe pump body but offset from axis 119 in a direction transverse to bothaxes. Elongate member 160 includes a hydrodynamic outer surface 165,i.e. a streamlined surface as seen in cross-section in FIG. 12. Thestreamlined surface 165 facilitates fluid flow within the left ventriclein the direction across elongate member 160.

In another variant as shown in FIG. 13, an elongate member 260 has aproximal end 261, a distal end 263 and a bore 262 therethrough. Elongatemember 260 is channel shaped and has an outer curved surface 265 and aninner curved surface 267. Distal end 263 is preferably connected to theinlet of the pump. As shown in a perspective view of elongate member 260in FIG. 14, outer surface 265 is designed to allow blood to easily passlengthwise along elongate member 260 as designated by the arrow withinthe channel and into the inlet of the pump. The inside diameter of thechannel may be similar to the diameter of the pump inlet. A member ofthis type may be connected the proximal end of the pump close to theaxis of the pump without occluding the flow of blood into the pump. Bore262 is designed to allow electrical power wiring extending from thestator of the motor to be housed within bore 262.

As shown in FIG. 15, an elongate member 360 is curved along the lengthof the member Elongate member 360 preferably has a bore 362 structuredto allow electrical power wiring to be housed and extend therethrough.

As shown in FIG. 16, the device may include a plurality of anchorelements 80 and elongate members 60. In this embodiment, the pluralityof elongate members will preferably have separate attachment points topump 20. Preferably, the elongate members 60 in this embodiment aresubstantially parallel to one another. Here again, anchor elements 80and the pump are fixed to elongate member 60 remote from one another sothat the elongate member maintain the pump in position relative to theanchor element.

Outflow cannula 40 may be replaced by a graft lumen material fixed topump 20 as described herein. The graft lumen may be homologous polyesterwith gel structure, or impregnated with heparin or thromboresistantmaterials, or augmented with targeted tissue ingrowth promotion factorssuch as collagen. Similar to the outflow cannula 40, the graft may betapered, fitted with a polymer tip, fashioned into a terminal tip. Thetip of the graft may be arranged to provide hydrodynamic self centeringas described above.

In a further embodiment, the outflow cannula 40 discussed above withreference to FIG. 1 may be provided with side holes (not shown)extending between the bore of the cannula and an exterior surface of thecannula proximal to the tip 70, in the region of the cannula which willlie within the aortic valve in the implanted condition. Such side holesdesirably have greater resistance to flow than the openings 72 of thecannula tip, so that the major portion of the blood flow from the pumpwill be directed out of the cannula through the tip. However, the bloodflow from the side holes tends to reduce impact between the leaves ofthe valve and the cannula, and to limit damage to the valve. Further, abolster or cuff (not shown) may be fitted to cannula 40 in a locationwhich will be disposed proximal to the leaves of aortic valve. Such abolster desirably is arranged to engage the aortic valve root anatomy tomaintain a centering force on the cannula and to some degree inhibitretrograde flow. However, such a bolster desirably does not fullyocclude forward flow through the aortic valve.

In still other embodiments, the outflow cannula may be non-circular andrather take the shape of other geometric configurations such astriangular, oval, elliptical, or the like. As shown in FIGS. 17-18,outflow cannula 140 is generally triangular in cross-section. Outflowcannula 140 may be straight or bent and desirably has an appropriatestiffness and hardness to accommodate the native heart and aortic rootgeometry and also to have non-traumatic contact with tissues. Hereagain, the cross-sectional dimensions of the cannula preferably taper tosmaller dimensions in the distal direction, away from pump body 20. Hereagain, the outflow cannula preferably projects through the aortic valvewhen the apparatus is implanted in a patient. Here again, the use of arelatively small cross-section at the aortic valve helps to minimizeaortic valve insufficiency, i.e. retrograde flow through the valve dueto poor sealing of the tri-leaflets around the cannula.

The triangular cross-section of outflow cannula 140 allows each of threeseparate outer surfaces of cannula 140 to engage a respective leaf 144of the tri-leaflet aortic valve. The generally triangular cross-sectionof cannula 140 is configured to allow for superior engagement of anouter surface of cannula 140 with the leaves 144 of the aortic valve.With the generally triangular cross-sectional shape, each leaflet of theaortic valve can engage a side surface of the cannula which is generallyflat or which has a large radius of curvature. This enhances the abilityof the valve to seal against the cannula. The fixation of anchor elementto the apex of the patient's heart also aids in inhibiting pump 20 fromrotating about its own axis 19 and therefore helps to maintain thedesired orientation of the outflow cannula 140, with each side surfacefacing a respective leaf of the aortic valve.

In a further embodiment depicted schematically in FIG. 19, the diffuserblades 128 of the pump, may be connected to a common hub 131 extendingalong the axis 19 of the pump. The diffuser blades and hub may befabricated as a separate unit, and this unit may be installed within thetubular housing 122 of the pump distal to the rotor 134.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. (canceled)
 2. A blood pump for intraventricular placement inside aheart of a mammalian subject comprising: a rigid elongate member havinga length between proximal and distal ends and a bore extending along thelength; an anchor element connected towards the proximal end of therigid elongate member and mounted to the subject's heart; a pumpcomprising an inlet and an outlet, a rotor and at least one electricdrive coil for magnetically driving the rotor, the pump connected at oradjacent to the distal end of the rigid elongate member remote from theanchor element; and wiring extending through the bore to the pump,wherein the proximal end of the rigid elongate member extends past theanchor element to a position outside of the subject's heart.
 3. The pumpof claim 2, wherein the proximal end of the rigid elongate memberincludes a fitting through which the wiring passes into the bore of therigid elongate member.
 4. The pump of claim 3, wherein the wiringextends from a source of electrical power, through the fitting of therigid elongate member, through the bore of the rigid elongate member,and to the at least one electric drive coil to drive the rotor of thepump.
 5. The pump of claim 3, wherein the fitting is a fluid-tightfeedthrough.
 6. The pump of claim 1 wherein the rigid elongate memberincludes at least one curve along at least a portion of its length. 7.The pump of claim 1, wherein the rigid elongate member is connected tothe inlet of the pump without occluding Hood flow into the inlet of thepump.
 8. The pump of claim 7, wherein the rigid elongate member isC-shaped forming an inner channel, and the bore has a cross-sectionalshape of a partial annulus, wherein an inner diameter of the channel issimilar to a diameter of the inlet of the pump such that blood can passlongitudinally along the channel and into the pump inlet.
 9. The pump ofclaim 7, wherein the rigid elongate member has an outer surface having across-sectional shape of a teardrop, wherein the outer surface of therigid elongate member is streamlined to facilitate fluid flow across therigid elongate member.
 10. The pump of claim 1, wherein the bore of therigid elongate member has a cross-sectional shape of a circle, partialannulus, or teardrop.
 11. A blood pump for intraventricular placementinside a heart of a mammalian subject comprising: a pump positionedwithin the heart, the pump comprising an inlet and an outlet, a rotorand at least one electric drive coil for magnetically driving the rotor;and wiring extending along a defined pathway from a location outside ofthe heart, through a wall of the heart and into a chamber of the heart,and to the at least one electric drive coil.
 12. The blood pump of claim11, wherein the defined pathway is in communication with the inlet ofthe pump without occluding blood flow into the inlet of the pump. 13.The blood pump of claim 11, wherein the defined pathway comprises a borethrough a conduit extending from the wall of the heart to the pump. 14.The blood pump of claim 13, wherein the bore is in communication withthe inlet of the pump without occluding Hood flow into the inlet of thepump.
 15. A method for intraventricular placement inside a heart of amammalian subject comprising: providing a pump having a housing definedbetween an inlet and an outlet; advancing the entirety of the pumphousing through a wall of the subject's heart and into a chamber of thesubject's heart; and extending wiring from a location outside of thesubject's heart, through the wall of the subject's heart, and to thepump to power the pump.
 16. The method of claim 15, wherein the step ofextending the wiring includes extending the wiring along a definedpathway to one of the inlet or outlet of the pump without occludingblood flow through the inlet or outlet of the pump.
 17. The method ofclaim 16, wherein the defined pathway is a bore extending axiallythrough a rigid elongate member extending from the pump to an anchorelement, the method further comprising the step of, after advancing theentirety of the pump through the wall of the subject's heart and intothe chamber of the subject's heart, mounting the anchor element to thewall of the subject's heart.
 18. new The method of claim 17, wherein thewiring is extended through the wall of the subject's heart through apassage in the anchor element through which the rigid elongate memberextends.
 19. A method for intraventricular placement inside a heart of amammalian subject comprising: providing an anchor element and a pumpconnected to a rigid elongate member remote from one another, the pumphaving an outflow cannula; advancing the pump through a wall in an apexof the subject's heart and into the left ventricle of the subject'sheart such that the outflow cannula extends from within the leftventricle through the aortic valve but terminates short of the arch ofthe aorta such that, other than the portion of the outflow cannulaextending through the aortic valve, the pump is positioned entirelywithin the left ventricle; mounting the anchor element to the apex ofthe subject's heart; and extending wiring from a location outside of thesubject's heart, through the anchor element at the apex of the subject'sheart, and to the pump to power the pump.
 20. The method of claim 19,further comprising a bore extending axially through the rigid elongatemember, wherein the step of extending the wiring includes extending thewiring through the bore of the rigid elongate member and to the pump.21. The method of claim 20, wherein one end of the rigid elongate memberextends past the anchor element to a position outside of the subject'sheart such that the portion of the wiring extending from a locationoutside of the subject's heart and through the anchor element ispositioned within the rigid elongate member therealong.
 22. The methodof claim 20, wherein the bore of the rigid elongate member is incommunication with the inlet of the pump without occluding blood flowinto the inlet of the pump.